Mathematical Flaw Exposed

Below is a mathematical argument that two is equal to one .

State the flaw in this argument.

In other words, a mathematical principle has been violated.

Explain this violation

Proving that 2 = 1

Assume that

a = b

Multiplying both sides by a,

a = ab

Subtracting b from both sides,

a - b = ab - b

Factorizing both sides,

(a + b)(a - b) = b(a - b)

Dividing both sides by (a - b)

a + b = b

If now we take a = b = 1, we conclude that 2 = 1